The present invention relates to a system for injecting a fluid, such as water or a water solution, into a supercharged internal combustion engine.
Various cooling fluids, such as water and water in solution with other substances, such as alcohols, including methanol, ethanol, etc., have been commonly injected into hydrocarbon engines, both of the spark-ignition and compression-ignition type, to provide improved engine operation. These improvements are possible since, during the compression stroke of the engine, the water droplets evaporate and thus absorb heat and prevent pre-ignition. On the power stroke, as the gasoline is burned the remaining water droplets and vapor are turned to steam which absorbs more heat and helps prevent detonation and the formation of nitrous oxides. Also, as the water turns to steam, it undergoes considerable expansion which produces significant additional power. Further, combustion occurs at lower temperatures and is more even, and the pistons and valves enjoy a longer life. Still further, the presence of water also creates a "steam cleaning" process that tends to remove carbon and other deposits from the combustion chamber, as well as prevent the formation of additional deposits.
Various types of prior art devices have been used to introduce cooling fluids into internal combustion engines. These devices have included nozzle-type injectors in which the fluid is pumped directly into the engine and intake air humidifiers in which air is passed through a volume of water before being introduced into the engine. However, since the injection of a relatively low volume of fluid is desired when compared to the volume of fuel introduced into the engine, it is difficult, if not impossible, to meter the fluid with the precision needed to insure optimum performance when it is pumped directly into the engine. Also, if humidified air is used, there is a reduction in power and fuel economy since the humidified air is less dense than an equal volume of dry air with water droplets. Also, the use of humidified air does not permit the cooling effect caused by the evaporation of the water droplets.
The use of supercharged engines, in which air is supplied to the engine intake at a relatively high pressure to increase the air charge weight and the power output of the engine, has long been recognized, especially in the high performance field. The use of superchargers has further highlighted the advantages of injecting cooling fluids into the engine since, for example, the adiabatic compression of the intake air by the supercharger raises the air charge temperature and therefore promotes detonation in the engine. However, the aforementioned prior art technique of pumping a stream of unatomized water directly into the carburetor, and therefore into the supercharger to reduce the temperature is unsatisfactory since the relatively heavy, unatomized water impinges on the impeller blades of the supercharger and causes corrosion and premature failure of the blades.